Welcome! This blog is inspired by the Gardena Willows Wetland Preserve in Gardena, California.

Tuesday, December 11, 2012

Why Do We Prune?

Why do we prune in gardens and in the Preserve?  Some reasons are obvious.  Diseased or damaged branches need to be removed as soon as possible to prevent the spread of disease.  Growth that presents a safety hazard must also be removed promptly.    But we prune plants for reasons other than safety and health.

One reason is to shape them.   If growing a hedge, we prune out  irregular branches in the beginning and then maintain the shape by regular hedge-trimming.   Similarly, we remove branches that grow in the wrong direction when training a new tree to a pleasant shape.   Some local gardeners take plant shaping to a high level, creating elaborately shaped shrubs in traditional Japanese or European styles.   These examples demonstrate the degree to which certain plants can be shaped.

Gardeners sometimes prune to control the size of trees and shrubs, often with limited success.  In general, plants continue to grow until they achieve their natural mature size.  They will keep trying to achieve this size – or die in the process. That’s why pruning to limit size is an endless task.  It’s far easier to choose a plant with the right natural size in the first place.  This is particularly important with California native shrubs, some of which become quite large.   But choosing a plant based on its mature size makes sense for any plant. 

Southern California’s native trees, shrubs and even grasses need to be pruned for another reason – to keep them youthful and healthy.   Hikers sometimes comment that wild shrubs appear to be pruned by an expert gardener.  In a way they are, but the ‘gardener’ is not who you might expect.

In truly wild areas, deer, rabbits, elk  - even wildfires, wind and water - prune plants on a regular basis.   Deer and elk browse the fresh growth of trees and shrubs in spring and summer.  Rabbits eat grasses and smaller vegetation.    The plants respond by producing new growth.  If the plant is not over-grazed, the result is a plant that’s fuller, more youthful and more attractive to the eye.

Fires also play a role in plant regeneration.  In the past, wildfires burned local foothills and mountains every 50 to 150 years depending on the area.  Fires are a consequence of our long dry summers and Santa Ana winds.  This weather pattern also occurs in other mediterranean climates like the Mediterranean region, South Africa, western Chile and western Australia.  

Plants from mediterranean climates have adapted to fires over the course of thousands of years.   Many mediterranean climate trees and shrubs have the capacity to re-grow after fires, allowing them not only to survive but also to rejuvenate themselves.    In fact, these plants are so dependent on fire that they literally need periodic fires to survive.   Without them – or their surrogate in the garden - they die prematurely.

Native Californians understood the need for periodic rejuvenation.  In the past, they regularly pruned, divided and even burned plants to keep them young and productive.  Over time, Native Californians became an integral part of the natural cycles of plant life.  They literally became a force of nature.

Most gardens and smaller nature preserves are no longer home to deer, rabbits and other forces of nature.  Even the wind patterns and water flow are altered in populated areas.   But the native plants still need the yearly and occasional catastrophic processes that keep them youthful and healthy.  And that’s where proper pruning plays a role.

Like the deer and rabbits, we need to prune back some of the fresh growth on native shrubs to encourage dense, well-shaped plants.   Like the wind, we need to prune out weak and damaged growth.   And like fire, we occasionally need to prune mature native grasses and some shrubs more harshly.   We literally ‘become’ the deer, rabbits, wind and fire for the native plants in our care.

Pruning native plants is not difficult, but you do need to know how to prune each plant.   Prune a native plant incorrectly – or at the wrong time of year – and you risk damaging or killing it.   The trick is to imitate the natural processes.  Many of us have little direct experience with these processes in the wild.  That means we need to learn how to prune our native plants. 

One easy way is to attend a pruning workshop at Mother Nature’s Backyard or the Gardena Willows Wetland Preserve.   The fall/winter pruning season is almost over, but we will have sessions in summer and again next fall.  See our schedule at http://www.gardenawillows.org/events.htm,   or call 310-217-0681.  Pruning classes are also given at CSU Dominguez Hills (see http://nativeplantscsudh.blogspot.com/p/calendar.html). 

For more information on pruning common California native plants see http://nativeplantscsudh.blogspot.com/2012/11/pruning-common-native-plants.html  or http://mother-natures-backyard.blogspot.com/2012/11/pruning-common-native-plants.html    A great book which includes information on pruning is California Native Plants for the Garden by Carol Bornstein, David Fross & Bart O’Brien (Cachuma Press, 2005). 



Constance M. Vadheim  (Adj. Professor of Biology – CSU Dominguez Hills; Board Member – Friends of Gardena Willows Wetland Preserve)

Friday, November 16, 2012

An Ugly View or Source of Inspiration?


We’re restoring the south-western section of the Preserve to the native Coastal Shrubland that once covered Gardena.  Towards that end, we planted hundreds of locally native plants near the amphitheater last spring.  On the positive side, the new plants are thriving.  The shrubs have grown several feet;  many have already flowered and set seed.  Insects, hummingbirds and seed-eating birds flock to the area.   And a place that once was bare – with a few non-native weeds – is well on its way to being restored.   But restoration is a bit like remodeling: once the remodel is completed, the whole house looks shabby around it.   And herein lays our source of inspiration.

English Ivy (lighter green) covering a Black Willow tree

The Preserve’s amphitheater sits on a gentle slope overlooking the wetlands.  It’s a nice venue for teaching, thanks to an Eagle Scout project in 2009.  It’s also a great place to sit and relax after a couple hours of weeding.  But the view from the amphitheater could – quite frankly - use some work!  As seen above, a few large non-native shrubs competed with the native willows and other wetland trees.  The area was overgrown with non-native English Ivy (Hedera helix – the same ivy many people have in their yards) was literally invading, climbing high into the trees and threatening their existence.  The front area was bare except for some weeds, non-native grasses and an unsightly-looking dead branch.  In short, it was not the kind of view we wanted from the amphitheater.

Fortunately, our young and enthusiastic volunteers love a challenge.  Last month – as part of our regular restoration day on the 3rd Saturday of each month – a group of students from the Gardena High School Honor Society and the Circle K Club from CSU Dominguez Hills tackled the view from the amphitheater.  They came in on the ground floor of the restoration process - a process that begins with assessing the area and setting restoration priorities.

After preliminary discussion, we decided to explore the area before setting restoration priorities.    Here’s what we found:
·         The area has lots of potential – the riparian woodland area is pretty and could provide wetland access  close to the teaching amphitheater

·         English Ivy is a huge problem – more extensive than we’d realized

·         Natural pathways exist in the area, but these are overgrown

·         The non-native shrubs are large and will take some work to remove

Large ivy trunk growing up a willow tree

As a group, we decided that ivy removal was the first priority:  ivy was spreading and threatening the native trees - and the problem would only get worse if nothing were done.   As a first step we cut the trunks of ivy growing up into the trees.  It took some work just to find the ivy trunks, even though some were several inches in diameter and stretched 20 feet or more into the trees.    Several weeks after cutting, the leaves were starting to die making it easier to see the remaining ivy.  We’ll tackle that in the future.

As we cut ivy, we decided to prune branches that were making ivy removal – and access in general – more difficult.   The branch trimmings are now being composed in the form of a brush pile.  The pile is located near enough to be useful for teaching, but far enough off the trail to hide it.    The brush pile will provide a hiding place for birds and lizards, as well as food for decomposing insects, worms, bacteria and other organisms.    The decomposed material will also return nutrients to the soil rather than removing them to the landfill.  We’ll be getting years of benefit from the pruning we did to provide access.  Now that’s smart restoration!

Area after first work day - bare but much nicer appearance

At the end of the morning, we sat back and admired the view from the amphitheater.  We could already see improvements.  The area was less overgrown, some of the ivy was gone and the ‘ugly branch’ had been turned into an interesting bit of native landscape.   But the front area still looked plain and empty – and we wanted it to eventually look pretty and interesting.  We decided that the trees provided a nice backdrop.  But we needed plants in front of them.   And we needed to plan ahead so we’d be ready to plant when the rains came.

We worked together to build a list of the types of plants/plant characteristics we wanted to include in the area.  Here’s what we came up with:

·         More leaf & flower colors

·         Small bushy purple plant (if possible)

·         Focus on plants native to the Gardena area

·         Increase the diversity and number of plants – shrubs, grasses, flowering plants

·         Fruit trees (native)

·         Include signage/information

·         Flowers

·         Include plants found in other parts of Preserve – especially those in surrounding Coastal shrubland area – to make the area seem part of the Preserve as a whole

At our November work day we’ll review the plant choices and develop a plant list.  Our goal will be to plant at least part of the front area in December/January while still leaving access for our on-going ivy removal.   The new plants will make the area look better while we continue our restoration of the interior sections.

At the end of the day, our ‘ugly view’ turned out to be something lovely – a source of inspiration.  It brought together a diverse group of students (and one professor) to solve real-life restoration challenges.  Many points of view are leading to practical and creative solutions.    And that’s a beautiful thing indeed! 


We’ll update you with our progress in the future. 


Saturday, October 13, 2012

Autumn’s Abundance

Living in the city – surrounded by non-native plants and foods from around the world – it’s easy to lose a sense of our local seasons. That’s unfortunate, because the cycle of seasons connects us to the place where we live. Seasonal changes give us a sense of  history and literally serve to ground us to our place on earth. Sometimes it takes a visit to nature to re-focus our attention on the joys – and the activities - of the current season. Wandering the Willows the other day, I encountered a reminder of Autumn’s abundance. What better example of the foods of Fall than a native rose bush laden with ripening fruit!

Our local native rose, California Wild Rose (Rosa californica) is a plant with several distinct seasons. In early spring, it sports a set of new leaves and delicate new sprouts. The fresh foliage is bright green and not yet hard and bitter. Native Californians harvested the tender sprouts in early spring and boiled or steamed them for a fresh vegetable.

In summer, California Wild Rose is in full glory. The leaves are green and mature. This is the perfect time to pick leaves for rose leaf tea. This delicate tea – made from fresh or dried leaves – has a flavor all its own. You can make rose leaf tea from any rose, including roses from your garden. Just be sure that the leaves haven’t been sprayed with pesticides. When you dry the leaves – and drink the tea – you’ll be participating in summer activities that have been part of many cultures for hundreds (perhaps even thousands) of years.

Summer is also when the pink rose flowers attract native bees, European Honey Bees and a variety of other pollinator insects. On a warm day, the smell of wild roses takes us back to pleasant summer days in a grandmother’s rose garden or hiking in our local wild lands. It is the essence of summer; and that fragrance and the sweet nectar is what attracts the pollinators. Wild roses are an important source of food (nectar and pollen) for summer’s insects.

Rose flowers are used and treasured in many cultures throughout the world. Like our ancestors, you can gather rose petals and dry them to preserve the fragrance of summer. The dried petals can be used in potpourri, sachets and even be used to brew a delightful pink tea. There’s nothing nicer than a cup of hot rose petal tea on a cold winter’s day. It brings back memories of summers past – and dreams of future summers.

The fruits of the Wild Rose (the ‘hips’) ripen in fall and winter. Rose hips are at their best when fully ripe. In colder climates, this happens after the first hard frost in the fall. In our mild climate, rose hips take a bit longer to mature. The best hint that rose hips are ripe is when the birds start to eat them - trust me, birds know when fruits are ripe!! Another hint is when the hips turn from orange-red to a dark red, become slightly soft and sweetly scented. The rose hips in the picture above are not yet fully ripe.

Rose hips are beautiful in their own right. They brighten a fall/winter landscape or garden with their dark red color in late fall. All roses produce rose hips, including garden roses. Most gardeners cut off aging rose flowers before the hips fully develop, so we don’t fully appreciate the fall season of the rose.

Roses develop hips for one purpose: to attract birds and animals which will eat the fruits and spread the seed. The rose hip is well suited this purpose. It’s red color says ‘here I am’ to passing birds and animals. The sweet taste of ripe rose hips provides a tasty treat. And the seeds are hidden inside the fruit, guaranteeing that at least some seeds will be eaten and spread, after a trip through a bird or animal’s intestinal tract (gut). Among the birds that eat rose hips are Mockingbirds and migratory Cedar Waxwings. Rabbits and small mammals also enjoy rose hips in fall/winter.

Rose hips are a treat for humans as well. Native Californians ate them fresh, cooked them for deserts and dried them whole or as ‘fruit leather’ for future use. Dried, ground rose hips make a tasty, healthy tea that’s loaded with vitamin C. Rose hip jelly is indescribably good and many old cookbooks include a recipe for this tasty treat. You can easily find recipes for making rose hip jelly on the internet. Rose hip syrup is easy to make and a tasty alternative on pancakes and desserts. All of these uses preserve autumn’s abundance for later enjoyment.

Using plants in old ways connects us to the land and its bounty. And observing the seasonal changes reminds us that we are just a part of nature’s great cycles. Come out to the Preserve soon and experience the joys of Fall.
Constance M. Vadheim (Professor of Biology – CSU Dominguez Hills; Board Member – Friends of Gardena Willows Wetland Preserve)

Monday, October 1, 2012

The Gardena Willows and CSU Dominguez Hills

A sampling site at the Gardena Willows Wetland Preserve

The connection between the Gardena Willows Wetland Preserve (GWWP) and CSU Dominguez Hills goes back many years, but it has developed greatly in the last few. Two members of the board of the Friends of the GWWP are faculty members in Biology, while another is a graduate student in Environmental Sciences. For the last 3 years, a group of undergraduates from Biology has worked every month at restoration days to remove fennel and castor bean, two of the most invasive of the non-native plants present. It is now quite hard to find specimens of either of these once-abundant plants at the preserve. In addition, there are several ongoing and past research projects supervised by CSUDH Biology faculty members at the preserve, on topics as diverse as improving restoration techniques, monitoring the aquatic invertebrates that inhabit the swamp, and the insects that are found in the Arroyo Willows. We will look more at these connections in future posts.

John Thomlinson   (Chair, Department of Biology - CSUDH; BoardMember - Friends of Gardena Willows Wetland Preserve)

Friday, September 21, 2012

In the Cool of the Willows

Today is typical September in S. California’s South Bay region.   The sun is warm and the humidity rising.  In short, it’s a perfect day to wander the shady paths of the Gardena Willows Wetland Preserve.   

The Preserve, located in south Gardena, is the last remaining remnant of the Dominguez Slough.  This seasonal wetland once covered areas now included in the cities of Gardena, Hawthorn and Carson as well as unincorporated areas of Los Angeles County.   The waters of Dominguez Slough once drained into Dominguez Creek and thence to the Los Angeles River and the Pacific Ocean.   The water that flows through the Gardena Willows Wetland Preserve today still drains into the Dominguez Channel (formerly Dominguez Creek), the Los Angeles River (also now channelized) and into the Pacific Ocean.

The Dominguez Slough has always been treasured as a cool, shady oasis in the hot Gardena Plain.  The trees of the riparian (near water) woodland could be seen for miles as a ribbon of inviting green.  The native inhabitants of the South Bay – the Gabrielino-Tongva people – used plants that grew in/around the wetland for food, shelter and other essentials.  South Bay settlers enjoyed the shade of the large Willows that grew there and favored the Slough as a place for summer picnics and boating.   What made Dominguez  Slough so inviting were the large willow, cottonwood and sycamore trees that surrounded the wetland.   Amazingly, you can see some of the old Willows even today!

The largest – and oldest - willows in the Preserve are Goodding’s Black Willows (Salix goodingii).  This    species is native throughout the U.S. Southwest and was named for Leslie Newton Goodding (1880-1967), a botanist and collector.  Goodding was one of the first to collect plants in what would later become the West’s famous national parks like the Grand Canyon, Yellowstone and the Great Tetons.  The common name ‘Black Willow’ refers to the tree’s bark, which is dark gray when wet.  Mature  Goodding’s Black Willows can grow to a height and width of 50 feet or more – and we have some large ones in the Preserve.  You can see the Black Willows towering above the other vegetation in the picture above.

Willows and other local riparian species are unique in their ability to survive both winter flooding and summer drought.  Black Willows usually grow right in the water for at least a few weeks/months in the winter.  Most  trees would die if their roots were under water for several months, but Goodding’s Willow thrives in these conditions and also survives the dry summer months, when streams and wetlands dry up entirely.    But adequate winter moisture to recharge the deep soil water is essential for their survival. 

Like many willows, Goodding’s Black Willows  are not particularly long-lived.  Compared to local native oaks (which live to 500+ years) Black Willows usually live only 50-75 years (though we have a few on the Preserve that are probably closer to 100 years old, with enormous trunks).   What is deceptive about willows is that while individual trunks may die, new trunks can arise from old trees.  So even a ‘young’ trunk can belong to a much older tree. 

Willows are dioecious, which means there are separate male and female trees.  We have both on the Preserve -  the only way you can tell them apart is when they bloom (more on the sex life of willows in the spring).   The leaves of the Goodding’s Black Willow look rather like a peach leaf (see below).  They are thin and medium green on both sides.  Another large willow in the Preserve – the Arroyo Willow – has thicker leaves that are shiny on top and white underneath.   Both lose their leaves in winter.

Humans have used Goodding’s Black and other willows for a long time.  Their wood is light and was used for making shelters/homes, cooking utensils (wood spoons) and even wooden legs.   Young stems were used in basket-making.   Both the leaves and bark were used to make medicinal teas.  These teas contained salicin (salicylic acid) which is the active ingredient in aspirin.   They were used for pain and fevers – much like aspirin is used today.


September 21, 2012                            Constance M. Vadheim  (Friends of Gardena Willows Wetland Preserve)